Many door cylinders or “closers” exist for controlling the closure of doors, particularly screen doors. These closers are generally designed to control the rate a door is opened and closed and many door closers are designed to lock a door in a selected open position.
A well known prior art door closer utilizes a cylinder connected at a first end to a door (or a door frame) with a spring loaded rod assembly extending from a second end. The second end of the cylinder is pivotally connected to the door frame (or door if the first end of the cylinder is connected to the door frame). Air enters the cylinder as the rod assembly is extended and the door is opened, and escapes through an adjustable orifice on the first end of the cylinder as the door is spring closed, thereby checking the rate of speed at which the door is spring closed with an air cushion action. The door can be held open by a hold open bracket carried on the rod. In normal operation, the hold open bracket is oriented in a “neutral” position to allow the rod assembly to retract into the cylinder when the door closes. When it is desired to keep the door partially or fully open, the hold open bracket is misaligned with the rod adjacent the second end of the cylinder to cause the rod and hold open bracket to bind against the cylinder (the “locked position”), keeping the rod assembly from retracting into the cylinder and effectively locking the door in an open position.
The hold open brackets are not always successful at preventing the rod assembly from retracting into the cylinder or allowing the rod assembly to be extended from the cylinder. Setting and/or maintaining the proper orientation of the hold open bracket is frequently the cause of these difficulties. Some prior art door closers have utilized a single spring to help bias the hold open bracket in a neutral or locked position, but these arrangements have not always proved successful.
Another problem with the prior art is that once the hold open bracket is oriented in its locked position, it is sometimes difficult to release the hold open bracket to permit the rod assembly to be retracted into the cylinder so the door can be closed. When the rod assembly is fully extended and the door closer is in the locked position, it is often particularly difficult to unlock the rod assembly.
Yet another issue with prior art door closers is that hold open brackets can also become greasy and dirty over time and it is undesirable to have to handle the hold open bracket. Further, handling of the locking mechanism can result in injury, such as pinched fingers.
Many prior art door closers rely on some retraction of the rod assemblies into the closer tube before the hold open bracket will fully engage the closer tube and lock the position of the rod assembly with respect to the closer tube. When the rod assembly retracts into the closer tube, it causes the door to swing towards its closed position. This reduces the width of the door opening. Further adjustments may be required to obtain the desired door opening width. In the case of a door that is being locked in a fully open position, this retraction of the rod assembly results in a loss of some of the available door opening width. This can be frustrating for the user if a greater door width is required, such as for moving large furniture through the door opening. Thus, there is a need for a door closer that will retain the door in its desired position when the hold open bracket is actuated. There is also a need for a door closer that will maintain a door in its fully open position without loss of door opening width due to retraction of the rod assembly back into the closer tube to actuate the hold open bracket.
Many modifications and improvements have been made in the art in an attempt to overcome these problems. For instance, mechanical levers have been utilized to provide better control of door closer locking washers or locking mechanisms and to avoid direct contact with greasy locking washers. U.S. Pat. No. 3,105,264 to J. A. Truhon discloses the use of a lever latch assisted by a single spring offset from, but generally parallel to, the longitudinal axis of the piston. U.S. Pat. Nos. 3,162,889 to R. J. Runnels and 6,634,058 to Lin disclose the use of a single release spring mounted over the piston rod, between the cylinder and the holding clip or retainer plate, to facilitate release of the holding clip or retainer plate. These devices are not effective to prevent the locking member and piston rod from getting dirty or protecting the user of the door control.
U.S. Publication No. 2003/0126716 in favor of Lin and U.S. Pat. No. 7,134,168 to Qing disclose the use of a cover, a lever and a single spring to facilitate setting of the washer and protection of the washer and user. These arrangements arguably may protect the user of the washer and prevent it from getting dirty. However, Qing provides a complicated mechanism for aligning the washer and Lin simply addresses leveraging of the locking washer by mounting an additional part on the piston that can also bind the operation of the piston.
U.S. Pat. No. 6,317,922 to Kondratuk discloses rotation of an end cap covering the exposed end of the piston rod to rotate a washer between a locked position and an unlocked position. A leg of the washer is moved into engagement with a raised surface of the cylinder end to lock the position of the piston rod and the same leg of the washer is moved into alignment with an inclined surface of the cylinder end to permit the piston to be extended from and refracted into the cylinder.
U.S. Pat. No. 6,615,449 to Alvarez discloses the use of a pair of concentric cups or caps positioned over the extended portion of the rod to move a flange member into a locked position. A flange member and a single spring are mounted on a rod in sliding relation, with the spring positioned on the side of the flange member adjacent the door control cylinder. The spring is intended to keep the flange member in a neutral position so that the rod can be retracted into the control cylinder. An inner cup is secured to an end of the control cylinder over the flange member and spring in sliding relation with the rod. The rod partially extends through an opening in the inner cup and is in sliding relation with the inner cup. An engagement pin is spring mounted on the inner cup to engage the flange member and move it to the locked position. The outer cup is mounted over the inner cup in sliding relation for movement towards and away from the inner cup. Upon movement of the outer cup towards the inner cup, the engagement pin is moved into engagement with the flange member to lock the piston in place with respect to the cylinder, preventing the rod from retracting into the control cylinder.
Applicant believes that the mechanisms described above and other prior art door controllers continue to experience problems of binding between the hold open bracket and the rod, maintaining the rod assembly in the locked position and unlocking the rod assembly. There continues to be a need for a simple way to operate door controller with an easy to set and release hold open bracket. The hold open bracket of the present invention is covered to protect the hold open bracket and to prevent injury to the operator and is easy to lock and unlock. The present invention is believed to address the shortcomings of the prior art and constitutes an improvement over the background technology.